The surface plasmon resonance phenomenon will be explored to develop a quantitative, sensitive, two-stage antibody assay system for reproductive hormones of clinical interest. The proposed approach can attain, with relatively inexpensive instrumentation, a sensitivity limit comparable to existing assay methodologies, without the use of dyes, radioisotopes or enzymes for specific signal generation. Part of the Phase I research work will entail choice of reagents and development of a compact optical instrument for performing simultaneous hormone quantifications of multiple serum samples using the surface plasmon immunoassay (SPI). During this stage of the research, human chorionic gonadotropin (HCG), will be used as a model hormone to characterize the assay performance in terms of sensitivity, specificity, accuracy and reproducibility. In Phase II study, the two-stage method will be extended to include other hormones of interest and the potential for rapid, in situ hormone determination for a one stage detection scheme will be investigated.